[jira] [Closed] (ARROW-8638) Arrow Cython API Usage Gives an error when calling CTable API Endpoints

["Wes McKinney (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-8638?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Wes McKinney closed ARROW-8638.
-------------------------------
    Resolution: Information Provided

Closing since there isn't a bug to fix, further discussion can take place here or on the mailing list

> Arrow Cython API Usage Gives an error when calling CTable API Endpoints
> -----------------------------------------------------------------------
>
>                 Key: ARROW-8638
>                 URL: https://issues.apache.org/jira/browse/ARROW-8638
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: C++, Python
>    Affects Versions: 0.16.0
>         Environment: Ubuntu 20.04 with Python 3.8.2
> RHEL7 with Python 3.6.8
>            Reporter: Vibhatha Lakmal Abeykoon
>            Priority: Blocker
>             Fix For: 0.16.0
>
>
> I am working on using both Arrow C++ API and Cython API to support an application that I am developing. But here, I will add the issue I experienced when I am trying to follow the example, 
> [https://arrow.apache.org/docs/python/extending.html]
> I am testing on Ubuntu 20.04 LTS
> Python version 3.8.2
> These are the steps I followed.
>  # Create Virtualenv
> python3 -m venv ENVARROW
>  
> 2. Activate ENV
> source ENVARROW/bin/activate
>  
> 3. pip3 install pyarrow==0.16.0 cython numpy
>  
>  4. Code block and Tools,
>  
> +*example.pyx*+
>  
>  
> {code:java}
> from pyarrow.lib cimport *
> def get_array_length(obj):
>  # Just an example function accessing both the pyarrow Cython API
>  # and the Arrow C++ API
>  cdef shared_ptr[CArray] arr = pyarrow_unwrap_array(obj)
>  if arr.get() == NULL:
>  raise TypeError("not an array")
>  return arr.get().length()
> def get_table_info(obj):
>  cdef shared_ptr[CTable] table = pyarrow_unwrap_table(obj)
>  if table.get() == NULL:
>  raise TypeError("not an table")
>  
>  return table.get().num_columns() 
> {code}
>  
>  
> +*setup.py*+
>  
>  
> {code:java}
> from distutils.core import setup
> from Cython.Build import cythonize
> import os
> import numpy as np
> import pyarrow as pa
> ext_modules = cythonize("example.pyx")
> for ext in ext_modules:
>  # The Numpy C headers are currently required
>  ext.include_dirs.append(np.get_include())
>  ext.include_dirs.append(pa.get_include())
>  ext.libraries.extend(pa.get_libraries())
>  ext.library_dirs.extend(pa.get_library_dirs())
> if os.name == 'posix':
>  ext.extra_compile_args.append('-std=c++11')
> # Try uncommenting the following line on Linux
>  # if you get weird linker errors or runtime crashes
>  #ext.define_macros.append(("_GLIBCXX_USE_CXX11_ABI", "0"))
> setup(ext_modules=ext_modules)
> {code}
>  
>  
> +*arrow_array.py*+
>  
> {code:java}
> import example
> import pyarrow as pa
> import numpy as np
> arr = pa.array([1,2,3,4,5])
> len = example.get_array_length(arr)
> print("Array length {} ".format(len)) 
> {code}
>  
> +*arrow_table.py*+
>  
> {code:java}
> import example
> import pyarrow as pa
> import numpy as np
> from pyarrow import csv
> fn = 'data.csv'
> table = csv.read_csv(fn)
> print(table)
> cols = example.get_table_info(table)
> print(cols)
>  
> {code}
> +*data.csv*+
> {code:java}
> 1,2,3,4,5
> 6,7,8,9,10
> 11,12,13,14,15
> {code}
>  
> +*Makefile*+
>  
> {code:java}
> install: 
>         python3 setup.py build_ext --inplace
> clean: 
>         rm -R *.so build *.cpp 
> {code}
>  
> **When I try to run either of the python example scripts arrow_table.py or arrow_array.py, 
> I get the following error. 
>  
> {code:java}
> File "arrow_array.py", line 1, in <module>
>  import example
> ImportError: libarrow.so.16: cannot open shared object file: No such file or directory
> {code}
>  
>  
> *Note: I also checked this on RHEL7 with Python 3.6.8, I got a similar response.* 
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